Fixed reference voltage circuitry based on bandgap voltage together with temperature compensation is widespread commercially available in the form of serial and shunt voltage regulators, and offers an initial accuracy typically down to 0.025% and a temperature drift of 2 ppm/C.
Often, reference voltages different from the standardized voltages are needed and in some cases even a stabilized, variable reference voltage is required. Typically, a stabilized reference voltage is obtained by resistor division as in FIG. 1, which can create an output voltage higher than the bandgap reference voltage. To ensure high initial accuracy and temperature drift corresponding to the bandgap reference specifications, the resistors (R2 and R3 in FIG. 1) shall be of very high precision with respect to the initial resistor value and have a very low temperature drift. Resistors of high precision and low temperature drift are very costly and typically cause the circuit to be economically non-viable.
US2014247023A1 discloses a technique to reduce the influence of resistor precision and temperature drift by adding an additional bandgap reference.
The present invention discloses a technique to obtain a reference voltage whose precision and drift are independent of the resistors in the circuit and which is without limits relative to the bandgap voltage, i.e., it can be above or below the bandgap voltage.